I think the dual version of the Double Knot is already discontinued (?).
That’s a side note. I use both the Double Knot and the Plumbutter though rarely at the same time.
The Double Knot is blue whereas the Plumbutter is wooden. Whereas the Double Knot can create some heavy or brutal rhythms, I find the Plumbutter more pastoral. Which device bubbles? They both can bubble but if I were to choose one for bubbling, I’d choose the Plumbutter.
Keep in mind, the Plumbutter is actually many instruments crammed into one box! That means it has complexities and complications which the Double Knot avoids by being more singular in focus.
If someone said: “I will cut off your arm unless you give up Double Knot or Plumbutter!” I would give up the Double Knot, personally, because I believe the Plumbutter has a greater range of possibilities for my particular style.
DO NOT MISTAKE ME. I love the Double Knot. Here is a phat track I dropped based around a Double Knot groove:
And here is a phat track I dropped which is 100% Plumbutter improvisation:
To draw this post to a close, both devices can create weird rhythms. A decision to purchase one or the other might be based on which sonic signature you prefer. I think the Double Knot has more anger whereas the Plumbutter has more levity. These are one man’s thoughts.